NTERNIST.ARC is a package which has been rediscovered in a pile of disks left over from a previous life as a medical software developer. It was acquired at a 1984 conference on medical software. This is undoubtably a test version. The BASIC source code has not been included. When you are asked to insert a reference disk and indicate which drive it is in, just use the drive the program is running on. This must be a method to deal with single sided floppy drives.